Bi-stability and period-doubling cascade of frequency combs in exceptional-point lasers

TL;DR

This paper analyzes the stability of frequency combs generated near exceptional points in lasers, revealing bi-stability and period-doubling cascades that enable new compact comb generator designs.

Contribution

It provides a stability analysis uncovering bi-stability and period-doubling phenomena in EP combs, advancing understanding of their dynamics and potential applications.

Findings

Discovery of bi-stability in EP combs

Identification of period-doubling cascade

Potential for compact frequency comb generators

Abstract

Recent studies have demonstrated that a laser can self-generate frequency combs when tuned near an exceptional point (EP), where two cavity modes coalesce. These EP combs induce periodic modulation of the population inversion in the gain medium, and their repetition rate is independent of the laser cavity's free spectral range. In this work, we perform a stability analysis that reveals two notable properties of EP combs, bi-stability and a period-doubling cascade. The period-doubling cascade enables halving of the repetition rate while maintaining the comb's total bandwidth, presenting opportunities for the design of highly compact frequency comb generators.